Light-sensitive blueprint layer and process of producing the same



Patented Aug. 1, 1950 LIGHT-SENSITI PROCESS P YE BLUEP PATENT OFFICE RINT LAYER AND RODUCING THE SAME Edward Jahoda, Manhasset, N. Y.

. N0 r n -Y Dplication'No NSerialNo. 709,7

. 3 Claims.

This invention relates to a light sensitive layer j and to th Blueprintlayer containing vember 14 86 that form the blue l of blueprint layers ci to be desigcolor of layer before ferric ferrous fem'eyanideferrocyanide Hated as exposure salts salts compounds compounds m. M M NN X Q X A-type yellow. X l X -type blue. X X O-type o.

X X X AB-type.. green, grey or blue. X X X AC-type green or blue. X X rX X ISO-type. blue. and intensity of the light andupon the duration TheA, B and C types are pure layers, the AB,

of the exposure. After the exposure the unexposed, and therefore, stillsoluble portions of the layer are removed by washing whereby the base islaid bare in the state general composi- 'Fe wmsis. Itcan be formedeomponents:

(A) Ferric'salts KB) Ferric salts :(C) Ferrous salt and ferrioyanide cand ferroeyanide c s and ferricyanide ompounds, ompounds,

compounds.

AC and BC type may be called mixed layers. At

ly the A-type layers C-type layers are t e A-type layers and the AB-ever as yet th they excel th depth of color of a perfect Wash-out. Ironsalts and ir as bulfers, oxidi wetting agents, etc., are emplo purposes,for instance, in order 121:. of the sensitizing solution, tration or tomodify its wetti 65 a 9, i rd s e? contra zers, thickeners, yed forvarious to stabilize the to reduce its peneng characteristics, 9r pe d.MW

stances have alkali oxalates, alkaline hydrolyzable alkali metal 'pureand mixed C-type layers is the improvement proved layers .including'varying amounts depending upon layer.

50% they do'affect the "therefore they can "printing speed of blueprintlayers.

' commercially a potassium composition under the tradename prove thekeeping qualities of the layer before the exposure, and to insure aproper wash-out of the soluble portions.

For all practical purposes good keeping qualities and a proper wash-outare just as important requirements of blueprint layers as a pleasingdark blue color obtained at satisfactory printing speeds.

Slow printing layers, especially of the A-type, usually have goodkeeping and wash-out qualities without requiring substantial amounts ofnonpigment forming substances; they contain a relatively large amount offree ferricyanide which, of itself, slows down the printing speed,contributes to the formation of the pigment, insures good keepingqualities, and facilitates the wash-out. Fast printing layers, however,especially those which are not of the A-type, contain little or no freeferricyanide. They require substantial amounts of non-pigment formingsubstances to improve the'keeping'and the wash-out qualities For thispurpose numerous subbeen employed, such as neutral of the layers.

compounds, acid hydrolyzable alkali metal phosphates, persulfatecompounds, sugarsand oxidizing agents. These substances'in the firstplace, tend to impair the duce the printing limited use on A, AB andB-type substances do not give satisfactory results on or do so only ifemployed in such large amounts as to offset the distinct advantages ofthe C-type layers.

It is the object of this invention to improve the keeping and wash-outqualities of blueprint layers without impairing color or printing speed.

Another more specific object of the invention of the keeping andwash-out mixed C-type bluelayers, these qualities of the pure and printlayers up to and above the standards set by the other types of blueprintlayers without impairment of, their advantages, particularly in respectto brilliancy of color, depth of color and latitude.

In other words, it is an-object of this invention :toovercome obstaclesnow in the way of'a'broad use of pure or mixed C-type blueprint layers.

A. further object of the invention .is an imlatitude blueprint paperwith. good. keep- 'ing and wash-out qualities.

I have found that the neutral ia'lkaliimetal hexametaphosphates impartexcellent keeping and wash-out qualities to all types of blueprint thepure and mixed 'C-type They can be used effectively in greatly the typeof Certain B-type layers do not require more than 5% ofhexametaphosphates by weight of the total solids, certain BC-type layersrequire as much as Up to 20%,these compounds do not affect measurablythe printing speed. Up to speed but do not affect visibly the brilliancyand the depthof the blue; be utilized to control the layers.

Neutral alkali metal hexametaphosphates are available as sodiumhexametaphosp'hate NazNaMPOzM, which is sold under the tradename Calgon(unadjusted grade), and as sodium hexametaphosphate of'the KzNaAPOsM orKNa5(POs)s, sold Plastic Metaphosphate. Whereas Calgon can 'wash-outqualities of ring in cc. of water. 3.8 grams of potassiumsodiumferricyanide and tion the Plastic Metaphosphate latitude.

thus the appearance of the blue color is improved. The use of PlasticMetaphosphate, therefore, dispenses with the need for other thickeners.

'Tentatively, the beneficial effects of the alkali metalhexametaphosphates on the keeping and blueprint layers may be attributedto the formation of complex molecules by the=same mechanismrthat causestheir effec- .tive peptizing and dispersing 1action upontmany solidmaterials, including heavy metal salts ;and oxides. It may be assumed:that the complex compounds formed are'fairly weak andtthat they.are'destroyed by the exposure to light, which also would account forthe fact that even large amounts of the alkali metal hexametaphosphateswill notimpair the brilliancy'and depth of the blue pigment.

The following examples are given to. illustrate my invention:

2.5 grams of Plastic Metaphosphate are dissolved at room temperatureunder vigorous stirring in cc. of water. To this solution are added anddissolved in conventional manner 4.5 grams of potassium oxalate, 20grams of iron ammonium oxalate and 5 grams of potassium ferrocyanide.

The resulting layer keeps very well even under unfavorable storingconditions, the wash-out is excellent. Without Plastic Metaphosphate thewashed-out portions of the layershow a considerable blue stain. .Calgonmay be substituted for the .Plastic Metaphosphata Example 2.-(C-typelayer of "slow printing :speed) .515 grams of PlasticMetaphosphate? aredissolved at room temperature under vigorous stir- Next there are addedthen4 grams of ferrous ammonium oxalate. The stirring. action must becontinued until the soluturns dark blue. This. solution must befilteredbut need notbe heated.

Theresulting layer hasgood'keeping, and washout qualities. WithoutIthePlastic Metaphosphate the Wash-out is very poor and the layer spoilscompletelywithin a very .few days even under ideal storing conditions. IIn this example acts alsoas speed Calgon' may be substitutedMetaphosphate.

reducing agent. for the "Plastic Example 3.--(BC-.type layer of ,fastsprinting speed) A solution prepared as in Example Land '5, solutionaccording: todsxample zgare mixed.

The; resulting layer :has an extremely great The keeping: and washf-outqualities, are better than. those of conventional layersof much be usedjust as well as 75 slower printing peeds.

The alkali metal hexametaphosphates used according to my invention areneither alkaline nor acid hydrolyzable salts. They are practicallyneutral and stable in solution. They can be used in excessive amountswithout impairing the blue pigment or staining the washed-out portions.

Alkaline hydrolyzable salts are able to improve the keeping and wash-outqualities of blueprint layers. Yet if used in more than in definitesmall amounts they affect the blue pigment under formation of brownishdecomposition products of basic iron. They tend to dull the blue colorand to stain the washed-out portions brownish.

Acid hydrolyzable salts are able to improve the wash-out qualities ofblueprint layers. Yet they are unable to improve the keeping qualities;if used in more than in definite small amounts they afiect the keepingqualities adversely. They tend to stain the washed-out portions bluish.

With the neutral alkali metal hexametaphosphates a hitherto unknownflexibility in the formulation of blueprint layers can be achieved.

What I claim is:

1. A sensitized solution having relatively high viscosity for ablueprint paper coating with a relatively reduced rate of penetrationinto the base paper containing approximately parts of neutralhydrolyzable potassium sodium hexametaphosphate, approximately 4 partsof alkali ferricyanide, and approximately 4 parts of a weak dissociableferrous salt in solution.

2. A sensitized solution having relatively high viscosity for ablueprint paper coating with a relati ely duced rate of penetration intothe base paper containing approximately 5%,; parts of neutralhydrolyzable potassiumv sodium hexametaphosphate, approximately 3 to 4parts of potassium sodium ferricyanide, and 4: parts of ferrous ammoniumoxalate in solution.

3. The process of producing a coating for blueprint paper having aviscosity high enough to reduce the rate of penetration into the basepaper comprising dissolving approximately 5 /2 parts of neutralhydrolyzable potassium sodium hexam-etaphosphate into approximatelyparts of Water, adding approximately 3.8 parts of potassiumferricyanide, adding approximately 4 parts of ferrous ammonium oxalateat room temperature, agitating the resultant solution until the solutionreacts to produce a dark blue color, and applying the resultant solutionto a paper base whereby a layer having good keeping and Washoutqualities is provided the blueprint paper.

EDWARD J AHODA.

REFERENCES CITED The following references are of record in th file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,093,738 Reynolds Sept. 21, 1937212G504 Reynolds Aug. 9, 1938 2,172,216 Miller Sept. 5, 1939 FOREIGNPATENTS Number Country Date 461,893 Great Britain Feb. 22, 1937

1. A SENSITIZED SOLUTION HAVING RELATIVELY HIGH VISCOXITY FOR ABLUEPRINT PAPER COATING WITH A RELATIVELY REDUCED RATE OF PENETRATIONINTO THE BASE PAPER CONTAINING APPROXIMATELY 5 PARTS OF NEUTRALHYDROLYZABLE POTASSIUM SODIUM HEXAMETAPHOSPHATE, APPROXIMATELY 4 PARTSOF ALKALI FERRICYANIDE, AND APPROXIMATELY 4 PARTS OF A WEAK DISSOCIABLEFERROUS SALT IN SOLUTION.